In order to meet the growing demands of the modern clinical laboratory to provide cost effective services, requiring that operating expenditures such as labor costs and cost of materials costs be reduced, reliance on low-cost disposable materials has increased. In addition, the use of automated clinical analyzers, which improve the efficiency of the laboratory procedures inasmuch as the operator has fewer tasks to perform and therefor reduce operating labor costs, has also increased.
The analysis of a test sample generally involves direct analysis of the test sample, or involves the reaction of the test sample with one or more reagents with respect to one or more analytes, wherein a reaction mixture is formed, either manually or by an automated instrument, comprising the test sample and one or more reagents. Generally, the test sample or reaction mixture is then deposited in a cuvette and read or otherwise analyzed by an analytical system or apparatus for one or more characteristics of the test sample. For example, in the case of an absorbance assay or a fluorescence polarization assay for determining the presence or amount of an analyte in a test sample, the absorbance or fluorescence polarization response of the reaction mixture, respectively, in a reaction cuvette is measured by the apparatus and, if analyte is present, correlated to the presence or amount thereof in the test sample. Analysis of a test sample or reaction mixture is typically accomplished by directing a beam of light or other source of energy into or through an optical read region of a cuvette containing the test sample or reaction mixture, and then detecting or measuring the resulting response therefrom.
In order to provide rapid turnaround and prevent cross-contamination of test samples, cuvettes are employed for a single analysis and are then discarded. Various assay cuvettes for the analysis of test samples have been described. In most instances, reaction cuvettes made from glass are employed for such analyses due to the physical properties of glass which permit reproducible and accurate results and which are required for performing various analyses, particularly absorbance assays and fluorescence polarization assays. However, the manufacture of glass reaction cuvettes is costly and, when used for only a single analysis and then discarded, together increase the cost of performing the analysis. In addition, breakage of glass during shipping or handling by a technician or processing by an instrument can result in injuries to the technician or operator or damage to the instrument employed to carry out a particular analysis. Since it is therefore desirable to employ disposable reaction cuvettes which are inexpensive to manufacture in order to reduce such costs, and which are durable during shipping and handling by a technician or operator of an instrument, plastic assay cuvettes have also been described. Although plastic assay cuvettes have be,an previously described, such plastic assay cuvettes may provide inaccurate results if they exhibit unsuitable optical properties, such as high birefringence. In order to overcome such unsuitable optical properties, plastic assay cuvettes have been described which are coined during the molding process. However, such molding process is practical only in the manufacture of substantially square or rectangular cuvettes in order to gain the advantages of the coining process. Moreover, such square or rectangular assay cuvettes are not readily adaptable to modern analytical instruments. For example, plastic assay cuvettes such as the Abbott Spectrum.RTM. Multicuvette and the Abbott VP.RTM. Multicuvette exhibit a birefringence level which exceeds those required when performing an assay with a glass cuvette, such as, for example, those requirements of the Abbott TDx.RTM. analyzer.
Accordingly, in order to meet the growing demands of the clinical laboratory to minimize the cost of various analyses which are performed in large volumes on a daily basis while, at the same time, provide accurate results, there is a need to provide reaction cuvettes which are disposable and which have the desired optical properties for use in a variety of analyses.